The present invention relates to a foundation formed from one or more layers of tyres. When the term xe2x80x9cfoundationxe2x80x9d is used herein, it includes any weight bearing surface such as a roadway, building foundation, railway track base, etc and any causeway including drainage floors, flow channels, drainage pit base, water sump, trickle filter base, bank way (including wave mat banks in water break walls) etc. The term xe2x80x9cfoundationxe2x80x9d is not intended to include retaining walls or the like (which are covered in the applicant""s co-pending application WO 98/49400), although various of those retaining walls are disclosed herein.
The use of tyres (especially used tyres) in retaining walls and retaining slopes is known. AU 10006/95 suggests a use for old tyres by providing a trench formed to accommodate the tyres in a side by side position to form a drain, tunnel, duct, ventilation shaft or the like.
FR 2643400 discloses a surface stabiliser formed from tyres set in straight lines and forming squares, with one tyre at each comer of a square. Alternatively, the tyres can be provided in staggered rows with adjacent tyres forming triangles. The tyres are bound together using natural synthetic fibres and can be filled with pieces of rock and covered, after laying, with rock or stones and a layer of soil to receive plants etc. However, FR 2643400 only discloses a single row of tyres, and does not disclose any structures which would be suitable for use in high load or highly erosive environments.
Similarly, RU 2060610 discloses a terracing arrangement employing used tyres in a staggered arrangement (FIG. 2 therein). Again, the arrangement disclosed in this document is not suitable for use in high load or highly erosive environments, but is concerned with providing a simple mat-type structure to prevent land erosion from rain.
NL 7706564 discloses a mattress for reinforcing an underwater structure. A plastic fabric has tyres secured thereto and a weighting material (a coarse rock) is positioned in those tyres. In such an arrangement, the coarse material is highly susceptible to ingress of fines material and thus breakdown. In addition, the tyres are simply provided to carry the weighting material so as to hold the plastics underlay in position. The arrangement is not concerned with load bearing applications.
SU 1312130 discloses a slope covering formed from old car tyres. The structure includes a protective earth layer reinforced with used tyres over which a stone material reinforcement layer, also reinforced with used tyres, is laid. Junction elements are provided between the tyre layers to join the two together. In addition, a polymer screen to prevent the earth layer from being leached from the structure is provided, but again there is nothing to suggest any substantial anti-erosive performance or load bearing capacity.
RU 2043455 discloses a road bed construction method which involves forming a mat of tyres which are secured in the lengthwise direction. The tyres are connected at their treads, are then covered with earth, peat or sand and are then covered with a geotextile layer. However, the construction does not prevent the ingress of fine materials into the mat, and thus would deteriorate over time.
In a first aspect the present invention provides a foundation comprising one or more layers of tyres including a lowermost layer being located adjacent to the ground, and a fill material provided within tyres of each of the layers, wherein at least the lowermost layer has a porous sheet positioned thereunder which is adapted for allowing the passage of water across the lowermost layer whilst preventing the ingress of matter of a grade finer than the fill material into the lowermost layer.
The porous sheet is provided to prevent deterioration of the fill material within the layer by the ingress of finer surrounding material. This arrangement contrasts strongly with those shown in SU 1312130 and RU 2043455, which disclose arrangements concerned with preventing the earth layer from being leached or washed away from the hydrotechnical structure disclosed therein.
In a second aspect the present invention provides a foundation comprising one or more layers of tyres including a lowermost layer being located adjacent to the ground on a geo-fabric material, with tyres in the lowermost layer having an upper sidewall removed therefrom and being provided with a fill material therewithin,
Wherein the lowermost layer is enclosed within the geo-fabric material, and further fill material and/or one or more further layers of tyres overlay the enclosed lowermost layer to define the foundation. By removing a side wall of at least some of the tyres, fill introduced therein can be compacted and thus such tyres can form a securing function in any structure in which they are used.
In a third aspect the present invention provides a method of construction on ground of a foundation as defined in the first and second aspects including the steps of:
forming one or more layers of tyres including a lowermost layer;
positioning on the ground a porous sheet which is adapted for allowing the passage of water across the lowermost layer whilst preventing the ingress of matter of a grade finer than the fill material into the lowermost layer;
locating the lowermost layer on the porous sheet adjacent to the ground; and
filling within tyres of each of the layers with the fill material.
Foundations constructed in accordance with the present invention can be suitably employed on: roads; ground or sub base such as sand and wetlands; drainage ways, courses and channels; railway track bases; mining tunnels; ramps and slopes adjacent to lakes, rivers, creeks, oceans; wave dissipation and breakwater walls; waste cell pits; stockpile bases, pavements; silt traps etc. All such environments are susceptible to erosion and deterioration through water saturation, and previous barriers employed
In the foundation and the method of constructing the same, it is preferred that the tyres within each of the layers are laid generally horizontally and are located adjacent to one another in a fixed array, each of the layers in conjunction with the fill material forming a tyre mattress. Such a xe2x80x9cmattressxe2x80x9d construction provides a very stable foundation base and tends to resist erosion and provide high load bearing capacity.
In the foundation, or method of constructing the same, at least two layers of tyres can be provided, and preferably each tyre in each layer has a sidewall removed therefrom so that the tyres can be oriented to be generally upwardly open in use to receive the fill material therein. When each tyre is open (having its uppermost sidewall removed therefrom) fill can be readily compacted in each tyre and an extremely stable and strong foundation can be constructed.
In the foundation and method of constructing the same, typically the fill material is a rock aggregate or cobble of a relatively coarse grade. Such fill can be susceptible to dislocation and movement in use if finer material (such as sand) penetrates into the foundation structure. This is because the fine material xe2x80x9clubricatesxe2x80x9d the rock and reduces the interlock between aggregate pieces. Hence the foundation in accordance with the invention is provided.
The number of layers employed in the foundation typically depends on the anticipated loadings and required stability of the foundation (eg when it is employed as an underlying road, ground or sub-base).
Typically, the lowermost layer is laid on the ground with minimal earthworks or sub-grade excavation being required. Advantageously, the foundation requires relatively low sub-grade stability and is thus suitable in marsh or swamp land and other wet areas. The layers of tyres or tyre mattresses can also be offset with respect to adjacent layers to provide distribution of the load between adjacent tyres whilst reducing the stability (bearing pressure capacity) requirements of the underlying ground or sub-base (eg. one tyre in one layer can overlay up to four tyres in an underlying adjacent layer).
Preferably, the fill material is a rock aggregate or cobble of a relatively coarse grade. In one example, the rock aggregate fill is of a nominal 75 mm diameter. . The relatively coarse fill material provides a porous layer having high drainage capacity. The relatively coarse fill material also combines with the tyres to minimise degeneration of the roadway or the drainage floor.
The performance of the coarse grade fill can deteriorate if fine material ingresses into the foundation, hence the employment of the porous sheets. Dislocation and movement of the rock aggregate can lead to potholes in gravel roadways etc. Thus typically, the lowermost layer or tyre mattress is wrapped in the porous sheet. In one example, the porous sheet is a porous cloth such as a geofabric cloth which also serves as a fire retardant.
When the foundation is used in a roadway or similar it can further comprise an edge support structure being configured to locate on opposing sides of at least an uppermost layer of the layers of tyres, the support structure acting so as to inhibit movement of the tyres and degeneration of the foundation. In one embodiment the edge support structure includes a row of support tyres being located alongside and coupled via a link structure to at least one side of eg. the uppermost layer of tyres.
Typically, the link structure includes a series of lateral tie elements each linking one of the support tyres to an adjacent tyre of the uppermost layer, and a longitudinal link element interconnecting the tie elements. In one example, the lateral tie elements and longitudinal link elements are constructed of tyre tread connected end to end or alternatively of conveyor belt material. However, other alternatives are also possible (detailed below).
The foundation can also comprise a series of drainage tyres located adjacent to one another within a trench excavated underneath the lowermost layer of tyres, and a drainage fill material can be provided within or between the drainage tyres. One or more drainage channels can extend from the trench so as to drain water away from the roadway or the drainage floor.
Typically the tyres employed as the basic constructional element have intact tread portions (i.e. a whole tyre is typically used, except that it may have an upper side wall removed therefrom. However, in some applications such as in drainage channels, silt traps etc, part tyres may be employed. For example, half a tyre, still having an upper side wall removed therefrom can be employed, and various other tyre segments can be employed.
In addition, tyres within the foundation can be further strengthened by arranging tyre portions therewithin as additional reinforcement. For example, in addition to fill material, a tyre with an upper sidewall removed therefrom can have one or more coiled tyre treads arranged therewithin, or a stack of tyre sidewalls arranged therewithin, or combinations thereof etc.
Silt trap foundations in accordance with the present invention can be formed by arranging a single lengthwise row of tyres, and by wrapping the row with lengths of tyre treads or conveyor belts to form an integrated and portable unit. Preferably such units have three tyres arranged end to end, each with an upper sidewall removed therefrom, and with tyre tread lengths extending right around and joined to the tyres.
In order to achieve a better understanding of the nature of the present invention several preferred embodiments of different foundation structures in accordance with the invention will now be described, together with construction methods therefor, by way of example only, with reference to the accompanying drawings in which:
FIG. 1 is a sectional view of a roadway according to one embodiment of the invention;
FIG. 2 is a schematic sectional view of another embodiment of a roadway of the invention;
FIG. 3 shows a plan view and a schematic sectional view of an edge support structure for use with the roadway of FIG. 1;
FIG. 4 shows a plan view and a schematic sectional view of an alternative edge support structure;
FIG. 5 is a sectional view of one embodiment of a drainage floor of the invention;
FIG. 6 is a sectional and enlarged sectional view of another embodiment of a drainage floor of the invention;
FIG. 7 is a plan view of part of the drainage floor of FIG. 6;
FIGS. 8 and 9, show respectively, plan and sectional side elevations (taken on the line 9xe2x80x949 of FIG. 8) of a double layer tyre reinforced pavement;
FIGS. 10 and 11 show views similar to those of FIGS. 8 and 9, but where the double layers form the sub-base of a stockpile pavement;
FIG. 12 shows a sectional elevation through a flow channel, being similar to the drainage floor shown in FIGS. 5 and 6;
FIGS. 13 and 14 show, respectively, end and side sectional elevations through a flow channel incorporating a weir and silt barrier therein, with FIG. 14 showing a view taken on the line 14xe2x80x9414 of FIG. 13;
FIGS. 15 and 16 show in side elevation, alternative bank protection foundations (wave mats), with FIG. 15 showing an aquaculture pond configuration and FIG. 16 a wave mat at a retaining wall (such as a seawall);
FIG. 17 shows a sectional elevation of an alternative wave mat arrangement for use with a retaining wall;
FIGS. 18, 19 and 20 show side, partial plan and sectional side elevations, respectively, (FIG. 19 taken on the line 19xe2x80x9419 of FIG. 18) of a trickle filter foundation for a stockpile of material or the like;
FIGS. 21 and 22 show similar views to FIGS. 18 and 19, but with a different tyre arrangement;
FIGS. 23 to 27 show various views of a waste disposal foundation in accordance with the invention wherein
FIG. 23 shows a plan view of one cell of the waste disposal foundation;
FIG. 24 shows a schematic plan detail of the cell showing an arrangement of tyres therein;
FIG. 25 shows a cross sectional side view through the cell of FIG. 23;
FIG. 26 shows a side elevation of part of the distribution channel shown in FIG. 24;
FIG. 27 shows a side cross-sectional view taken on the line 27xe2x80x9427 of FIG. 26;
FIG. 28 shows a plan view of a tyre with a side wall removed therefrom;
FIG. 29 shows, schematically, a side perspective view illustrating the removal of a tyre sidewall;
FIG. 30 shows a plan view of an alternative means for xe2x80x9cremovingxe2x80x9d a side wall of the tyre (by splitting the tyre horizontally through its tread);
FIGS. 31 to 36 show plan elevations of various ways of arranging and binding the tyres in mattress formations within various foundations in accordance with the present invention; and
FIGS. 37 to 42 show alternative edge support structures for use with a roadway or other foundation, being alternatives to those structures shown in FIGS. 3 and 4;
FIG. 43 shows a side elevation of a causeway structure foundation, FIG. 44 showing the same elevation in cross section, and
FIG. 45 showing a cross section through part of the causeway, illustrating a drainage configuration;
FIG. 46 shows in side elevation an alternative roadway and drainage foundation structure,
FIGS. 47 and 47A show respectively a detail and plan view of the arrangement of FIG. 46;
FIG. 48 shows a plan view of a tyre for use in a foundation and that has been reinforced internally in accordance with the present invention;
FIG. 49 shows a sectional view through the tyre of FIG. 48 taken on the line 49xe2x80x9449;
FIG. 50 shows a plan view of a roadway constructed using tyres according to FIG. 48,
FIGS. 51 and 52 show sectional elevations through the roadway, for two alternative roadway embodiments;
FIG. 53 shows an alternative bank protection foundation incorporating tyres in accordance with FIG. 48,
FIG. 54 shows a side sectional elevation through the bank protection foundation of FIG. 53;
FIG. 55 shows a plan elevation of a foundation in the form of silt barrier units arranged in a drainage causeway in accordance with the present invention,
FIGS. 56 and 57 show, respectively, end and side sectional elevations through the arrangement of FIG. 55;
FIG. 58 shows an individual silt barrier unit foundation in perspective view and associated with a drain;
FIG. 59 shows an alternative silt barrier foundation to that of FIG. 58 when located in a V drain configuration.